üçlü

Etymology
From, equivalent to.

Adjective

 * 1) with three parts; with three members, triple, tripartite, trilateral

Noun

 * 1) trio
 * 2)  a playing card with the number three
 * 3)  threesome

Usage notes
It's also common to say "üçlü grup seks" or only "grup seks" for threesome.